The present invention relates to an expansible anchor made of metal, and to a method for the manufacture thereof.
The expansible anchor comprises a shank part having means for holding or fixing an article at its rear end and an expander cone at its front end having expansible segments separated from each other by slots. The expander cone widens from a reduced cross-section towards the front end until it has a diameter approximately the same as the shank diameter.
German Published Patent Application DE-OS 35 26 784 A1 discloses an expansible metal anchor which has a shank part provided with an external thread and an expander cone. An expansible sleeve provided with a continuous longitudinal slot is pulled over the expander cone. The sleeve is resiliently deformable and has an external diameter larger than the diameter of the shank. As the expansible anchor is driven into the hole drilled in the anchoring substrate, the expansible sleeve is pressed together until of the diameter of the drilled hole. The expansible sleeve is consequently fixed in the drilled hole so that an axial displacement of the shank part draws the expander cone into the fixedly held expansible sleeve to expand the latter. Anchoring of the expansible anchor is therefore only possible if the shank part and the expansible sleeve are displaceable with respect to one another and at the same time the expansible sleeve is capable of being fixed in the drilled hole.
With the known metal expansible anchors, this is achieved when the expansible sleeve and the shank part are manufactured as separate parts and are joined together in an assembly operation. The shank part is normally manufactured by a turning method or as a cold extruded part, while the expansible sleeve is manufactured from sheet metal as a stamped and bent part. The respective manufacturing processes of the individual parts restrict firstly the potential configurations of the parts, and cause considerable time to be expended and considerable expense to be incurred in the manufacture and assembly of the expansible anchor.